The present invention relates to circuit breakers, and more particularly to an extended rotary operating mechanism to operate a circuit breaker.
Circuit breakers, both single and multi-phase circuit breakers, are typically mounted in equipment cabinets. A typical electrical equipment cabinet includes a front closing door. In some instances, a handle of a circuit breaker protrudes through openings in the cabinet door and can be operated directly. In some applications it is desirable to provide an extended handle operating mechanism. The extended operating mechanism is coupled to the operating handle of the circuit breaker by a shaft.
In operation, the extended handle operating mechanism moves the circuit breaker operating handle to its various operative positions. For example, an xe2x80x9cONxe2x80x9d position, and xe2x80x9cOFFxe2x80x9d position and xe2x80x9cRESETxe2x80x9d position. In some instances, it is necessary to lock the extended operating mechanism in an xe2x80x9cOFFxe2x80x9d position. However, in some instances, when the electrical contacts of the circuit breaker have become welded closed, usually as a result of a short circuit condition, locking the extended operating mechanism in an xe2x80x9cOFFxe2x80x9d position would create a dangerous and inappropriate condition since an operator would believe that the circuit breaker is in the xe2x80x9cOFFxe2x80x9d (electrical contacts open) condition, when in fact the electrical contacts are welded closed.
Thus there is a need for an extended rotary operating mechanism for a circuit breaker that will prevent the extended operating handle from being locked in an xe2x80x9cOFFxe2x80x9d position when the electrical contacts of the circuit breaker are in fact closed, such as in a welded closed condition.
There is provided an extended rotary operating mechanism for a circuit breaker having a movable operating handle coupled to a shaft and electrical contacts, the extended rotary operating mechanism comprising a handle operator defining a socket. A blocking plate mounted in the socket, with the blocking plate including a blocking shape. A shaft adapter is coupled to the blocking plate and the shaft. If the electrical contacts of the circuit breaker are welded closed and a torque is applied to the operator handle, the blocking shape prevents the handle operator from being locked in an xe2x80x9cOFFxe2x80x9d position independently of the operating handle position, by covering a locking hole. The shaft adapter may include one of an extended socket and a recessed socket configured to engage the shaft.
There is also provided a method for preventing an operating handle of the circuit breaker from being locked in an xe2x80x9cOFFxe2x80x9d position when electrical contacts of the circuit breaker are welded closed. The circuit breaker has a shaft coupled to the operating handle. The method comprises the steps of providing a handle operator having a socket and a mounting plate defining a locking hole providing a blocking plate having a blocking shape and configured to fit in the socket. A shaft adapter coupling the shaft adapter to the blocking plate and the shaft. Covering the locking hole with the blocking shape when a torque is applied to the handle operator.
There is further provided an extended rotary operating mechanism for a circuit breaker having a movable operating handle coupled to a shaft, and having electrical contacts. The extended rotary operating mechanism comprises a means for rotating defining a socket. A means for blocking mounted in the socket. A means for coupling operatively connected to the means for blocking and the shaft. Wherein, if the electrical contacts of the circuit breaker are welded closed and a torque is applied to the means for rotating, the means for blocking prevents the means for rotating from being locked in an xe2x80x9cOFFxe2x80x9d position, independently of the operating handle position, by covering a locking hole.